DragonflyBSD on Areca w/ HAMMER

Dean Hamstead dean at fragfest.com.au
Tue May 31 16:35:47 PDT 2011

Well, there is a possibility to add and remove volumes other than the
root volume, but IMHO
it's still considered experimental. In combination with LVM you could
emulate expanding and
shrinking of a Hammer filesystem.
In my case, the underlying raid card can expand the volumes it presents 
to the operating system as a 'disk' without changing data.

This can also be replicated by dd'ing a small disk to a large disk, or 
expanding the disk size in a virtual machine.

In freebsd, i can add a new disk to the raid set and expand the volume 
live (thats the card). Unmount /dev/da0 (i format the disk raw, rather 
than slicing it), rescan for devices - the disk is re-detected as being 
bigger- then i run growfs /etc/da0. mount that volume and off i go.

obviously im not mounting /dev/da0 as /, otherwise unmounting it would 
go rather badly.

So basically im looking to do the same with HAMMER. But gaining 
snapshots and dedeplication etc over UFS.




On Tue, May 31, 2011 at 1:07 AM, Dean Hamstead<dean at fragfest.com.au>
Hi Guys

Im thinking about reloading my home file server with dragonflybsd.
Mainly so
i can take advantage of the rather awesome looking HAMMER filesystem.
My home server has an Areca 1260 SAS raid card, which is reported as
supported by the arcmsr man page.
Im looking for confirmation from other users that areca cards work
well, and
that the admin tools are supported from freebsd or otherwise implemented
Also id like to get some feedback that HAMMER is up to the task of being
belted really hard over sustained periods.
Im also not able to see find a conclusive answer to if HAMMER can be
expanded (as im relatively frequently adding more disks, and
expanding my
raid array - currently im using UFS tool growfs)
I have dabbled with ZFS on freebsd, but found it wanting. HAMMER
seems much
more 'next generation' - rather than just collapsing some raid
features in
to the filesystem.


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